US4709220A - Radiation suppression device - Google Patents

Radiation suppression device Download PDF

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Publication number
US4709220A
US4709220A US06/903,974 US90397486A US4709220A US 4709220 A US4709220 A US 4709220A US 90397486 A US90397486 A US 90397486A US 4709220 A US4709220 A US 4709220A
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US
United States
Prior art keywords
coil
deflecting coil
magnetic field
deflection yoke
auxiliary coil
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US06/903,974
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English (en)
Inventor
Toshihiko Sakane
Michio Ogasa
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sharp NEC Display Solutions Ltd
Original Assignee
Mitsubishi Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP60203779A external-priority patent/JPS6264024A/ja
Priority claimed from JP1985153830U external-priority patent/JPH0735287Y2/ja
Priority claimed from JP60232666A external-priority patent/JPS6293841A/ja
Priority claimed from JP1985168601U external-priority patent/JPS6274743U/ja
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Assigned to MITSUBISHI DENKI KABUSHIKI KAISHA, 2-3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO, JAPAN A CORP. OF JAPAN reassignment MITSUBISHI DENKI KABUSHIKI KAISHA, 2-3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO, JAPAN A CORP. OF JAPAN ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: OGASA, MICHIO, SAKANE, TOSHIHIKO
Application granted granted Critical
Publication of US4709220A publication Critical patent/US4709220A/en
Assigned to NEC-MITSUBISHI ELECTRIC VISUAL SYSTEMS CORPORATION reassignment NEC-MITSUBISHI ELECTRIC VISUAL SYSTEMS CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: MITSUBISHI DENKI K.K.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/70—Arrangements for deflecting ray or beam
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/003—Arrangements for eliminating unwanted electromagnetic effects, e.g. demagnetisation arrangements, shielding coils
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/0007—Elimination of unwanted or stray electromagnetic effects
    • H01J2229/0015—Preventing or cancelling fields leaving the enclosure

Definitions

  • the present invention relates to an undesired radiation suppression device which causes the decay of a harmful and unnecessary magnetic field that is irradiated externally from a deflection yoke of a cathode ray tube in a display monitor or the like, and more particularly to a radiation suppression device that is provided with an erasing coil for extinguishing a leak magnetic field.
  • the regulated undesired radiation frequency which is demanded by the VDE (Verband Deutscher Elektrotechniker) standard in West Germany shall be over 10 KHz and it has been an unsolved problem for a cathode ray tube display unit to deal with, inter alia, unnecessary radiation that is produced by a horizontal deflection current.
  • the production of the unnecessary radiation results from a leak magnetic field generated by a deflecting coil through which the horizontal deflection current flows, a flyback transformer, a horizontal separation control coil and a horizontal linearity control coil.
  • the unnecessary radiation quantity that is irradiated outward consists of a certain proportion amounting to about 70 percent in the deflection yoke, about 20 percent in the flyback transformer and about 10 percent in other horizontal separation control coils and the like.
  • FIG. 1a is a side view of a deflection yoke 1 showing only a core 1a and a horizontal deflecting coil 1b.
  • FIG. 1b is a front view of the horizontal deflecting coil 1b observed from the front side, that is, from the side of the funnel of a cathode ray tube 2.
  • a magnetic field is produced instantaneously in the direction shown by a dotted line arrow.
  • the horizontal deflection magnetic field 6c is produced in the vertical direction in the space surrounded by the core 1a and at the same time a separate leak magnetic field 6a, 6b is produced at the crossover coil portion 1c, 1d before and after the horizontal deflecting coil 1b which is to be irradiated in the external space (FIG. 1c).
  • FIG. 2 is a partly cut-away perspective view showing a prior art cathode ray tube provided with radiation suppression device.
  • the source of undesired radiation such as the deflection yoke 1 mounted onto the cathode ray tube, the flyback transformer (not shown) and the like is surrounded by a chassis 3, a radiation plate 4 and a cover plate 5 that are composed of a metal plate with good electrical conductivity or a magnetic material, and the leak magnetic field is confined to the inner portion to reduce the level of undesired radiation irradiated outwardly to the external portion.
  • the prior art radiation suppression device has a structure in which the source of undesired radiation is surrounded by the above-described magnetic shield plate, the display monitoring apparatus is not only restricted to a considerable extent from the view point of structure, but there are also problems in that the efficiency of heat radiation of the apparatus is low and the apparatus is high in cost.
  • the present invention provides an auxiliary coil which is connected in series or in parallel with said deflecting coil on the outer wall face of said yoke corresponding to the winding position of said deflecting coil.
  • the auxiliary coil produces a magnetic field capable of cancelling the leak magnetic field of the deflecting coil in response to a scanning frequency whereby the leak magnetic field of the deflecting coil in response to a scanning frequency whereby the leak magnetic field of the above-mentioned deflecting coil is negated.
  • the above-described deflecting coil may, for instance, be a horizontal deflecting coil.
  • the above-described auxiliary coil is wound and formed in a saddle-shape. Accordingly, in the present invention, the undesired radiation signal stemming from the deflecting coil of a cathode ray tube can be reduced drastically and, if the scanning frequency goes high, the electrical performance of the deflecting coil is subject to no risk or harm, making it possible for the suppression device to respond easily thereto.
  • the present invention provides a radiation suppression device having an auxiliary coil for cancelling the leak magnetic field that is produced from the deflecting coil including a plurality of wire hanger portions that are formed with a definite form at a predetermined position on the outer face or surface of the front and rear portions of a separator which constitutes a deflection yoke, the wires being hung over and wound around the wire hanger portions.
  • the device since the device has a structure wherein a plurality of wire hanger portions are provided on the separator, the wires being wound around the wire hanger portions to form the auxiliary coil, a non-modified auxiliary coil can be simply mounted at the precise position of the deflection yoke and the level of undesired radiation from the deflection yoke can be reduced remarkably.
  • a plurality of wire hanger portions are, preferably, composed of a groove which is formed on the outer circumferential surface of the front portion of the separator covering the front crossover line portions of the horizontal deflecting coil, depressed portions that are formed at two opposed points on the outer circumferential surface of the front portions of the separator, and hooks that are formed on the circumferential surface and the back face of the rear portion of the separator which covers the rear crossover line portions of the deflecting coil.
  • the present invention provides holding means for holding an auxiliary coil that is movably mounted on the wall face of the outer circumference of the deflection yoke and is connected electrically to the deflecting coil. Based upon the fact that the auxiliary coil is movable, the distribution form of the magnetic field produced therefrom can be varied, thus allowing undesired magnetic field to be effectively cancelled in response to a complicated change of the magnetic field due to, for example, the reflection of the undesired magnetic field of the deflecting coil.
  • the present invention is advantageous in that, since the auxiliary coil is held movably the device can be adapted even if the structure of the housing is modified without adversely affecting the function of radiation suppression and thus is always able to achieve the maximum suppression effect with respect to the undesired radiation.
  • FIG. 1a is a side elevational view showing the configuration of the core of a deflection yoke and a horizontal deflecting coil used in a prior art cathode ray tube display unit;
  • FIGS. 1b and 1c are explanatory diagrams illustrating a leak magnetic field of the horizontal deflecting coil in FIG. 1a;
  • FIG. 2 is a partly cut-away perspective diagram of the prior art cathode ray tube display unit having radiation suppression device
  • FIG. 3a is a side elevational view showing a radiation suppression device mounted onto a deflection yoke as an embodiment of the present invention
  • FIGS. 3b and 3c respectively show the distribution of magnetic lines of force at one side of and in a cross-sectional view of the deflection yoke shown in FIG. 3a;
  • FIGS. 4a, 4b and 5 are, respectively, circuit diagrams showing examples of electrical connections between an auxiliary coil and a deflecting coil of the radiation suppression device shown in FIG. 3a;
  • FIG. 6 is a perspective view showing an auxiliary coil of the radiation suppression device which can be easily mounted, as another embodiment of the present invention.
  • FIG. 7 is a partly fragmentary side view showing a separator for use in an embodiment as shown in FIG. 6;
  • FIG. 8 is a rear elevational view showing a separator for use in an embodiment as shown in FIG. 6;
  • FIG. 9 is an explanatory diagram illustrating the fact that when a metal plate exists around the deflection yoke, undesired radiation produced form a deflecting coil is nonsymmetrical;
  • FIG. 10 is a schematic side view showing a still further embodiment of the radiation suppression device in accordance with the present invention, in which the position of an auxiliary coil is adjustable;
  • FIG. 11 shows each principal component of the embodiment shown in FIG. 10.
  • FIG. 12 is a graph showing the cancelling effect with respect to undesired radiation achieved by the radiation suppression device according to the present invention in comparison with the prior art example.
  • FIGS. 3a to 3c, FIG. 4 and FIG. 5 show one embodiment of the present invention.
  • an auxiliary coil 7 is mounted on the outer wall face of a core 1a such as to cover a horizontal deflecting coil 1b held within the core 1a of a deflection yoke 1 between coils 7 and 1b.
  • the auxiliary coil 7 which has a number of turns equivalent to between 8% and 10% the number of turns of the horizontal deflecting coil 1b is wound in a saddle form closely similar to the horizontal deflecting coil 1b, and has coil sides 7a and 7b which are formed parallel to the crossover line portions 1c and 1d of the horizontal deflecting coil 1b.
  • the coil side 7c disposed parallel to the axis line of the auxiliary coil 7 is fixed such as to extend in the axial direction along the outer face of the core 1a.
  • the number of turns and the winding direction of the auxiliary coil 7 and the electrical connection with the horizontal deflecting coil 1 b are in advance so selected that, when a horizontal deflecting current passes through the auxiliary coil 7 and the horizontal deflecting coil 1b, magnetic fields 8a and 8b shown by a dotted arrow in FIG. 3b are produced so as to cancel leak magnetic fields 6a and 6b produced from the crossover line portions 1c and 1d of the horizontal deflecting coil 1b.
  • FIGS. 4a and 4b, and FIG. 5 show examples of the electrical connection in such cases.
  • the auxiliary coil 7 can be connected in series with the horizontal deflecting coil 1b (FIG. 4a and FIG. 4b).
  • the rectilinear portion within the core 1a in the horizontal deflecting coil 1b produces a definite direction of magnetic field in the space within the core as an effective field (deflection field), as shown in FIG. 3c.
  • the leak magnetic fields 6a and 6b are irradiated outwardly.
  • auxiliary coil 7 is connected as shown in FIG. 4a or FIG. 4b and an upper half of coil 7 and a lower half coil 7 are, respectively, wound such as to form a counter magnetic field which is reverse in direction to that of the magnetic field of the corresponding deflecting coil 1b, the magnetic fields 8a and 8b are produced and act to cancel the above-described leak magnetic field.
  • the auxiliary coil 7 is mounted on the outside of the deflection yoke 1, the influence brought about by the auxiliary coil 7 can be inhibited by the core 1a with regard to the magnetic field in the space which is surrounded by the core 1a as shown in FIG. 3c.
  • the effect created by the leak magnetic field 9 in the rectilinear portion is so small as to be ignored as an undesired signal level with respect to the outer space.
  • the horizontal scanning frequency is likely to be high and thus the impedance of the horizontal deflecting coil is reduced.
  • FIG. 6 shows another embodiment of the present invention which enables an auxiliary coil of the radiation suppression device in accordance with the present invention to be mounted easily.
  • 1e denotes a vertical deflecting coil and 10 a separator.
  • the above-described groove 11 and depressed portions 12 constitute a first wire hanger portion 14 which is wound around the coil side 7a of the front side of the auxiliary coil 7.
  • hooks 13a and 13b form a second wire hanger portion 13 around which the coil side 7b of the auxiliary coil 7 is wound.
  • the auxiliary coil 7 is wound and formed simply by a predetermined number of turns of the wires around and through the hooks 13b and 13a, the corner between the depressed portion 12 and the groove 11, the groove 11, the depressed portion at the opposite side, the hook at the opposite side and the original hook 13b in that order.
  • the winding work can be done simply, the position of the auxiliary coil 7 is correct, and the wire so wound is held reliably by the wire hanger portions 13 and 14 without causing difficulties such as deformation or the like.
  • the winding work in accordance with the present invention is simple and easy and auxiliary coils 7 having consistent quality in their ability to cancel the undesired magnetic field can be formed into marketable products.
  • FIG. 7 is a side view showing a partly exploded separator 10 employed in the above-described embodiment
  • FIG. 8 is a rear elevation viewing the separator 10 from the rear.
  • the wire hanger portions 13 and 14 are formed by the groove 11, depressed portions 12 and hooks 13a and 13b. Also, pins for preventing the wire from falling off may be employed in place of the groove 11, while grooves 10d may be formed on the outer circumferential surface 10b of the rear portion of the separator 10 in place of the hooks 13a and 13b.
  • the present invention allows the undesired magnetic field which is irradiated outwardly when the scanning current flows through the deflecting coil 1b to be cancelled by the magnetic field produced by the auxiliary coil 7 which has a form as similar to the deflecting coil as possible.
  • a deflection yoke including the radiation suppression device of the present invention is, in fact, put into a housing, when the deflection yoke is surrounded at some distance from its circumference by a metal sheet 15 (FIG. 9), the undesired magnetic field 6 produced by the deflecting coil is reflected under the influence of the metal sheet 15, and the distribution of the magnetic field becomes asymmetrical both in the vertical direction and in the horizontal direction.
  • FIGS. 10 and 11 show a still further embodiment of the present invention which enables the undesired magnetic field to be cancelled effectively by means of the auxiliary coil even when the undesired magnetic field irradiated from the deflecting coil is asymmetrical.
  • the numeral 16 denotes a fixture for installing the deflection yoke 1 together with the auxiliary coil 7, and an elongated slit 17 is formed in this fixture 16.
  • the fixture 16 is rotated in the clockwise direction or in the counter-clockwise direction with respect to the central axis of a cathode ray tube 1 and is fixed by screws 18 at the position where the cancelling effect with respect to the undesired magnetic field is the highest.
  • the intensity of the magnetic field produced by the auxiliary coil 7 is not affected so much by the environment, since the number of turns of the auxiliary coil 7 is extraordinarily small in comparison with that of the deflecting coil. Accordingly, the distribution of the magnetic field in the auxiliary coil is similar to that of the undesired magnetic field shown in FIG. 1c.
  • the asymmetrical undesired magnetic field shown in FIG. 9 when the auxiliary coil 7 is rotated in the clockwise direction or in the counter-clockwise direction around the central axis of the cathode ray tube 1, the magnetic field produced form the auxiliary coil is also rotated and becomes asymmetrical compared to what is shown in FIG. 3a.
  • the range of adjustment in this case is about ⁇ 10° of the rotational angle.
  • the elongated slit 17 of the fixture 16 is arranged in advance so that the position of the auxiliary coil 7 itself may be finely adjusted to-and-fro.
  • FIG. 12 demonstrates the cancelling effect with respect to the undesired radiation based upon the radiation suppression device in accordance with the present invention; the level of undesired radiation is denoted in each case in curve (a) when means for suppressing the undesired radiation from the deflecting coil is not installed; in curve (b) when the magnetic shielding shown in FIG. 2 is implemented; and in curve (c) when the radiation suppression device of the present invention is installed.
  • This graph demonstrates that at the frequency of 31.5 KHz, the level of undesired radiation is reduced by 10 dB in the case of curve (b) and by 15 dB in the case of curve (c), as compared with the case of curve (a).

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
US06/903,974 1985-09-13 1986-09-04 Radiation suppression device Expired - Lifetime US4709220A (en)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
JP60-168601 1985-08-01
JP60203779A JPS6264024A (ja) 1985-09-13 1985-09-13 不要輻射防止装置
JP60-203779 1985-09-13
JP60-153830 1985-10-08
JP1985153830U JPH0735287Y2 (ja) 1985-10-08 1985-10-08 偏向ヨーク
JP60-232666 1985-10-17
JP60232666A JPS6293841A (ja) 1985-10-17 1985-10-17 不要輻射防止装置
JP1985168601U JPS6274743U (de) 1985-10-30 1985-10-30

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US4709220A true US4709220A (en) 1987-11-24

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US06/903,974 Expired - Lifetime US4709220A (en) 1985-09-13 1986-09-04 Radiation suppression device

Country Status (3)

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US (1) US4709220A (de)
KR (1) KR900001503B1 (de)
DE (1) DE3631023A1 (de)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4922167A (en) * 1985-10-25 1990-05-01 U.S. Philips Corporation Picture display device having means for compensating line stray fields
US4947083A (en) * 1985-10-25 1990-08-07 U.S. Philips Corporation Picture display device with interference suppression means
EP0401831A1 (de) * 1989-06-09 1990-12-12 Kabushiki Kaisha Toshiba Kathodenstrahlrohreinrichtung zur Verringerung von magnetischen Streuflüssen ausserhalb der Einrichtung
US5065186A (en) * 1990-05-03 1991-11-12 Ncr Corporation Magnetic emissions reduction apparatus and method
US5189348A (en) * 1989-06-09 1993-02-23 Kabushiki Kaisha Toshiba Cathode ray tube apparatus intended to reduce magnetic fluxes leaked outside the apparatus
US5208510A (en) * 1991-12-30 1993-05-04 Zenith Electronics Corporation CRT magnetic field cancelling device
US5382875A (en) * 1992-08-10 1995-01-17 Zenith Electronics Corporation Stray magnetic field suppresser for CRT image displays
US5399939A (en) * 1992-01-03 1995-03-21 Environmental Services & Products, Inc. Magnetic shield with cathode ray tube standoff for a computer monitor
US5406240A (en) * 1987-06-05 1995-04-11 Deckers; Francois E. Device to reduce the hazards of surrounding electromagnetic radiation
US5430351A (en) * 1992-04-09 1995-07-04 Kabushiki Kaisha Toshiba Cathode-ray tube apparatus with means for reducing leakage magnetic field
US5448212A (en) * 1992-12-30 1995-09-05 Murata Mfg. Co., Ltd. Deflection yoke device
US5561333A (en) * 1993-05-10 1996-10-01 Mti, Inc. Method and apparatus for reducing the intensity of magnetic field emissions from video display units
US5563476A (en) * 1990-11-27 1996-10-08 International Business Machines Corporation. Cathode ray tube display
US5594615A (en) * 1993-05-10 1997-01-14 Mti, Inc. Method and apparatus for reducing the intensity of magenetic field emissions from display device
US5675213A (en) * 1995-11-16 1997-10-07 Chunghwa Picture Tubes, Ltd Cathode ray tube deflection yoke with reduced electric field radiation from terminal pins of printed circuit board on yoke
US5815361A (en) * 1995-04-03 1998-09-29 Samsung Electronics Co., Ltd. Magnetic field shielding device in display
US6424085B1 (en) * 1998-07-21 2002-07-23 U.S. Philips Corporation Cathode ray tube having a deflection unit
US6498435B1 (en) * 1998-10-07 2002-12-24 Furuno Electric Co., Ltd. CRT display device to suppress electromagnetic radiation therefrom

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0485559U (de) * 1990-11-29 1992-07-24
DE3704648C3 (de) * 1986-02-17 1997-09-18 Murata Manufacturing Co Ablenkjocheinheit mit Hilfsspulen zur Verringerung unerwünschter Abstrahlung
US4853588A (en) * 1986-09-05 1989-08-01 Denki Onkyo Co., Ltd. Deflection yoke apparatus with means for reducing unwanted radiation
NL8701109A (nl) * 1987-05-11 1988-12-01 Philips Nv Beeldweergeefinrichting met strooiveld-compensatiemiddelen.

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Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4922167A (en) * 1985-10-25 1990-05-01 U.S. Philips Corporation Picture display device having means for compensating line stray fields
US4947083A (en) * 1985-10-25 1990-08-07 U.S. Philips Corporation Picture display device with interference suppression means
US5406240A (en) * 1987-06-05 1995-04-11 Deckers; Francois E. Device to reduce the hazards of surrounding electromagnetic radiation
US5189348A (en) * 1989-06-09 1993-02-23 Kabushiki Kaisha Toshiba Cathode ray tube apparatus intended to reduce magnetic fluxes leaked outside the apparatus
EP0401831A1 (de) * 1989-06-09 1990-12-12 Kabushiki Kaisha Toshiba Kathodenstrahlrohreinrichtung zur Verringerung von magnetischen Streuflüssen ausserhalb der Einrichtung
US5065186A (en) * 1990-05-03 1991-11-12 Ncr Corporation Magnetic emissions reduction apparatus and method
US5563476A (en) * 1990-11-27 1996-10-08 International Business Machines Corporation. Cathode ray tube display
US5734234A (en) * 1990-11-27 1998-03-31 International Business Machines Corporation Cathode ray tube display with deflection yoke and radiation shield
US5208510A (en) * 1991-12-30 1993-05-04 Zenith Electronics Corporation CRT magnetic field cancelling device
US5399939A (en) * 1992-01-03 1995-03-21 Environmental Services & Products, Inc. Magnetic shield with cathode ray tube standoff for a computer monitor
US5430351A (en) * 1992-04-09 1995-07-04 Kabushiki Kaisha Toshiba Cathode-ray tube apparatus with means for reducing leakage magnetic field
US5382875A (en) * 1992-08-10 1995-01-17 Zenith Electronics Corporation Stray magnetic field suppresser for CRT image displays
US5448212A (en) * 1992-12-30 1995-09-05 Murata Mfg. Co., Ltd. Deflection yoke device
US5594615A (en) * 1993-05-10 1997-01-14 Mti, Inc. Method and apparatus for reducing the intensity of magenetic field emissions from display device
US5561333A (en) * 1993-05-10 1996-10-01 Mti, Inc. Method and apparatus for reducing the intensity of magnetic field emissions from video display units
US5815361A (en) * 1995-04-03 1998-09-29 Samsung Electronics Co., Ltd. Magnetic field shielding device in display
US5675213A (en) * 1995-11-16 1997-10-07 Chunghwa Picture Tubes, Ltd Cathode ray tube deflection yoke with reduced electric field radiation from terminal pins of printed circuit board on yoke
US6424085B1 (en) * 1998-07-21 2002-07-23 U.S. Philips Corporation Cathode ray tube having a deflection unit
US6498435B1 (en) * 1998-10-07 2002-12-24 Furuno Electric Co., Ltd. CRT display device to suppress electromagnetic radiation therefrom

Also Published As

Publication number Publication date
KR870003547A (ko) 1987-04-18
KR900001503B1 (ko) 1990-03-12
DE3631023A1 (de) 1987-03-26
DE3631023C2 (de) 1988-09-29

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